During the process of a biological sampling program for Mississippi's Estuarine Inventory, data on the spawning season and influx of young were compiled for the two species of silversides found in Mississippi estuarine waters, Menidia beryllina (Cope) and Membras martinica (Valenciennes). Silversides taken from collections made with seines, beam trawls, plankton nets and dip nets were measured and the condition of the gonads noted. These data, when combined with associated field observations, first revealed ripe male and female Menidia beryllina (68 mm to 98 mm) in late March (water temperature 23.9°C) and Membras martinica (66 mm to 79 mm) in early April. M. beryllina in spawning condition were collected in salinities ranging from 3.6'/00 to 31.5%0 and water temperatures ranging from 23.9°C to 32.7·C throughout the spring and summer months. Spawning M. martinica were collected in salinities from 9.4 °/00 to 31.1·00 and in water temperatures from 21.2·C to 30.7°C. Postlarval atherinids (4.5 mm to 9 mm) were taken in plankton tows in late March and early April. Juvenile Menidia beryllina (14 mm) first appeared in early April. Juvenile Membras martinica (26-31 mm) were first collected in early May. These observations from the Mississippi coast parallel those of other workers reporting on atherinid spawning elsewhere along the Gulf and Atlantic coasts of the United States.
